全文获取类型
收费全文 | 176536篇 |
免费 | 3354篇 |
国内免费 | 568篇 |
专业分类
化学 | 86611篇 |
晶体学 | 1316篇 |
力学 | 8925篇 |
综合类 | 5篇 |
数学 | 47834篇 |
物理学 | 35767篇 |
出版年
2023年 | 720篇 |
2022年 | 898篇 |
2021年 | 1309篇 |
2020年 | 1460篇 |
2019年 | 1490篇 |
2018年 | 11635篇 |
2017年 | 11270篇 |
2016年 | 8988篇 |
2015年 | 3670篇 |
2014年 | 3257篇 |
2013年 | 6660篇 |
2012年 | 10098篇 |
2011年 | 16363篇 |
2010年 | 9452篇 |
2009年 | 9216篇 |
2008年 | 11932篇 |
2007年 | 13776篇 |
2006年 | 5317篇 |
2005年 | 6051篇 |
2004年 | 5599篇 |
2003年 | 5291篇 |
2002年 | 4001篇 |
2001年 | 2274篇 |
2000年 | 2124篇 |
1999年 | 1493篇 |
1998年 | 1244篇 |
1997年 | 1113篇 |
1996年 | 1415篇 |
1995年 | 968篇 |
1994年 | 1036篇 |
1993年 | 1017篇 |
1992年 | 991篇 |
1991年 | 867篇 |
1990年 | 882篇 |
1989年 | 790篇 |
1988年 | 746篇 |
1987年 | 722篇 |
1986年 | 668篇 |
1985年 | 941篇 |
1984年 | 863篇 |
1983年 | 641篇 |
1982年 | 747篇 |
1981年 | 735篇 |
1980年 | 654篇 |
1979年 | 615篇 |
1978年 | 575篇 |
1977年 | 514篇 |
1976年 | 577篇 |
1974年 | 516篇 |
1973年 | 533篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
The structure, chemical composition, and magnetic properties of electrochemically deposited nanocrystalline Co-Ni-Fe films
were investigated using a number of techniques. A high saturation magnetic induction up to B
s
= 21 kG was attained. An enhancement of the saturation magnetization compared to the ideal anticipated one was revealed,
which correlated with the nonlinear behavior of the structural phase composition and lattice parameters with the change of
the composition.
The text was submitted by the authors in English. 相似文献
3.
4.
5.
NaY zeolite samples loaded with sodium metal by vapor phase deposition have been investigated using129Xe NMR spectroscopy. At low sodium concentration, the129Xe NMR spectrum showed three resonance lines which clearly indicate the existence of distinct domains in the zeolite sample. Such an observation suggests that the diffusion of the xenon atoms into each domain only occurs with respect to the NMR time scale (2.9 ms). As the sodium concentration increases, observation of a single broad line indicate a macroscopic homogenization of the system. The shift of this line is explained in part due to a paramagnetic interaction between the xenon atoms and the unpaired electrons of particles containing an odd number of sodium atoms. The linewidth is due to the distribution of the local magnetic fields partially averaged by the rapid motion of the xenon atoms and to the statistical distribution of the sodium particles in the supercage cavities. The paramagnetic interaction vanishes with the oxidation of the sample leading to a narrowing and a shift of the line to higher magnetic fields. 相似文献
6.
7.
8.
Eduard Feireisl Antonín Novotný Hana Petzeltov 《Mathematical Methods in the Applied Sciences》2002,25(12):1045-1073
We prove a general compactness result for the solution set of the compressible Navier–Stokes equations with respect to the variation of the underlying spatial domain. Among various corollaries, we then prove a general existence theorem for the system in question with no restrictions on smoothness of the spatial domain. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
9.
A forecasting model is developed for the number of daily applications for loans at a financial services telephone call centre. The purpose of the forecasts and the associated prediction intervals is to provide effective staffing policies within the call centre. The model building process is constrained by the availability of only 2 years and 7 months of data. The distinctive feature of the data is that demand is driven in the main by advertising. The analysis given focuses on applications stimulated by press advertising. Unlike previous analyses of broadly similar data, where ARIMA models were used, a model with a dynamic level, multiplicative calendar effects and a multiplicative advertising response is developed and shown to be effective. 相似文献
10.